EP0175068B1 - Method for producing an aerosol stream - Google Patents

Method for producing an aerosol stream Download PDF

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Publication number
EP0175068B1
EP0175068B1 EP85107856A EP85107856A EP0175068B1 EP 0175068 B1 EP0175068 B1 EP 0175068B1 EP 85107856 A EP85107856 A EP 85107856A EP 85107856 A EP85107856 A EP 85107856A EP 0175068 B1 EP0175068 B1 EP 0175068B1
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Prior art keywords
aerosol
stream
silicon dioxide
fluorine
free
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EP85107856A
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German (de)
French (fr)
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EP0175068A2 (en
EP0175068A3 (en
Inventor
Dietrich Eisbrenner
Hans Merk
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Licentia Patent Verwaltungs GmbH
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Licentia Patent Verwaltungs GmbH
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Priority to AT85107856T priority Critical patent/ATE49188T1/en
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/01413—Reactant delivery systems
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/08—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant
    • C03B2201/12—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant doped with fluorine

Definitions

  • Such a method is known from EP-A1-0 116 342.
  • a method for producing a preform for optical fibers is described, in which at low temperatures, e.g. B. 20 ° C, glass-forming chlorides, e.g. B. SiC1 4 and / or GeC1 4 , with steam in a flame-free reaction to a glass-forming layer, for. B. Si0 2 -soot, are implemented.
  • This glass-forming layer is on a suitable carrier body, for. B. a graphite tube, so that a preform is formed from which an optical waveguide can be drawn.
  • Doping SiO 2 with germanium causes an increase in the optical refractive index of Si0 2 .
  • a method for producing a preform is known from US Pat. No. 4,062,665, in which small undoped and / or doped SiO 2 particles are deposited on the end face of a rotating cylindrical body.
  • the Si0 2 particles are generated and deposited using a high-temperature burner which generates a temperature of at least 1200 ° C.
  • a so-called glass soot is deposited, which is sintered in a further process step, so that a preform is formed from which an optical waveguide can be drawn.
  • VAD procedure vertical axial deposition
  • a method is described which is particularly suitable for the production of so-called preforms for optical fibers made of quartz glass.
  • a silicon dioxide (Si0 2 ) -containing aerosol stream is generated by chemical conversion of gaseous silicon tetrachloride (SiCl 4 ) and water vapor (H 2 0) in a reactor at 500 ° C to 1,000 ° C.
  • SiCl 4 gaseous silicon tetrachloride
  • H 2 0 water vapor
  • the aerosol stream there is a rod-shaped carrier body on which the Si0 2 particles are deposited. It is necessary to create layers with different optical refractive indices. This is done by doping the Si0 2 particles.
  • the Si0 2 particles are generated in a reactor in a temperature range from 500 ° C. to 1000 ° C. by means of a hydrolysis reaction according to the formula
  • Doping Si0 2 particles produced in this way is only possible with dopants that can be incorporated into the quartz matrix under the reaction conditions mentioned.
  • a dopant is, for example, germanium oxide (Ge0 2 ), which increases the refractive index of Si0 2 . This doping takes place with the aid of a hydrolysis reaction according to the formula which proceeds analogously to formula (1).
  • the invention is therefore based on the object of developing a generic method in such a way that, in the case of an SiO 2 -containing aerosol stream, doping of the Si0 2 particles contained therein is possible, which causes a reduction in the optical refractive index in Si0 2 .
  • a first advantage of the invention is that when using CF 2 CI 2, the resulting fluorine is incorporated into the Si0 2 particles. An unsafe controllable surface adsorption is avoided.
  • a second advantage is that a high fluorine concentration is achieved in the silicon dioxide, so that the optical refractive index can be greatly reduced.
  • Si0 2 particles according to formula (1) are produced. These SiO 2 particles have a diameter of approximately 0.3 ⁇ m and are referred to in the specialist literature as glass soot or with the English expression “soot”.
  • Various fluorine-containing gases and / or vapors are added to the vaporous silicon tetrachloride (SiCl 4 ) in certain proportions and the resulting glass soot ( «soot») is examined for its fluorine content. The result is shown in the following table:
  • CF 2 CI 2 shows a doping effect of a desired magnitude.
  • CF 4 and SF s result in negligible fluorine doping, probably because these gases do not decompose appreciably at a temperature of 700 ° C.
  • An important result is that the fluorine content (after doping with CF 2 CI 2 and after a sintering process) is largely preserved. This can be interpreted as an indication that the fluorine has actually been incorporated into the SiO 2 particles and that there is not only superficial adsorption.
  • the specified fluorine doping in the range of 1.0 mol% to 1.8 mol%, a reduction in the optical refractive index of 0.35% to 0.57% is possible with Si0 2 .

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Chemistry (AREA)
  • Colloid Chemistry (AREA)
  • Manufacture, Treatment Of Glass Fibers (AREA)
  • Glass Melting And Manufacturing (AREA)
  • Glass Compositions (AREA)
  • Silicon Compounds (AREA)
  • Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)
  • Medicines Containing Material From Animals Or Micro-Organisms (AREA)
  • Agricultural Chemicals And Associated Chemicals (AREA)
  • Medicinal Preparation (AREA)

Abstract

A method for producing a directed aerosol stream from gaseous and/or vapor phase reactants by conveying the gaseous and/or vapor phase reactants including vaporous silicon tetrachloride, water vapor, and at least one vaporous, fluorine-containing hydrocarbon to a reaction site; reacting the reactants at the reaction site in a flame-free chemical reaction to produce an aerosol composition constituted of solid silicon dioxide particles which include silicon dioxide doped with fluorine, whereby the optical index of refraction of the solid silicon dioxide particles is reduced; and causing the aerosol composition to flow as an aerosol stream from the reaction site and immediately surrounding the aerosol stream with a moving, essentially aerosol-free, gas and/or vapor stream to form a directed aerosol stream enveloped in the aerosol-free stream.

Description

Die Erfindung betrifft ein Verfahren zur Herstellung eines Aerosolstromes nach dem Oberbegriff des Patentanspruchs 1.The invention relates to a method for producing an aerosol stream according to the preamble of patent claim 1.

Ein derartiges Verfahren ist bekannt aus der EP-A1-0 116 342. Dort wird ein Verfahren zur Herstellung einer Vorform für Lichtwellenleiter beschrieben, bei welchem bei niedrigen Temperaturen, z. B. 20 °C, glasbildende Cloride, z. B. SiC14 und/oder GeC14, mit Wasserdampf in einer flammenfreien Reaktion zu einer glasbildenden Schicht, z. B. Si02-soot, umgesetzt werden. Diese glasbildende Schicht wird auf einem geeigneten Trägerkörper, z. B. einem Graphitrohr, niedergeschlagen, so daß eine Vorform entsteht, aus der ein Lichtwellenleiter gezogen werden kann. Eine Dotierung von SiO2 mit Germanium bewirkt eine Erhöhung des optischen Brechungsindexes von Si02.Such a method is known from EP-A1-0 116 342. There, a method for producing a preform for optical fibers is described, in which at low temperatures, e.g. B. 20 ° C, glass-forming chlorides, e.g. B. SiC1 4 and / or GeC1 4 , with steam in a flame-free reaction to a glass-forming layer, for. B. Si0 2 -soot, are implemented. This glass-forming layer is on a suitable carrier body, for. B. a graphite tube, so that a preform is formed from which an optical waveguide can be drawn. Doping SiO 2 with germanium causes an increase in the optical refractive index of Si0 2 .

Aus der US-A-4 062 665 ist ein Verfahren zur Herstellung einer Vorform bekannt, bei welchem auf der Stimfläche eines rotierenden zylinderförmigen Körpers kleine undotierte und/oder dotierte Si02-Teilchen abgeschieden werden. Die Erzeugung und Abscheidung der Si02-Teilchen erfolgt mit Hilfe eines Hochtemperaturbrenners, der eine Temperatur von mindestens 1 200 °C erzeugt. Es wird ein sogenannter Glasruß (« soot ») abgeschieden, der in einem weiteren Verfahrensschritt gesintert wird, so daß eine Vorform entsteht, aus welcher ein Lichtwellenleiter gezogen werden kann.A method for producing a preform is known from US Pat. No. 4,062,665, in which small undoped and / or doped SiO 2 particles are deposited on the end face of a rotating cylindrical body. The Si0 2 particles are generated and deposited using a high-temperature burner which generates a temperature of at least 1200 ° C. A so-called glass soot is deposited, which is sintered in a further process step, so that a preform is formed from which an optical waveguide can be drawn.

Ein solches Verfahren wird auch VAD-Verfahren (« vertical axial deposition ») genannt.Such a procedure is also called VAD procedure (“vertical axial deposition”).

In der nichtvorveröffentlichen EP-A-0 134 507 die unter Artikel 54(3) EPÜ fällt, wird ein Verfahren beschrieben, das insbesondere geeignet ist zur Herstellung von sogenannten Vorformen für Lichtwellenleiter aus Quarzglas. Dazu wird durch eine chemische Umsetzung von gasförmigem Slliciumtetrachlorid (SiCl4) und Wasserdampf (H20) in einem Reaktor bei 500 °C bis 1 000 °C ein Siliciumdioxid (Si02)-haltiger Aerosolstrom erzeugt. In dem Aerosolstrom befindet sich ein stabförmiger Trägerkörper, auf welchem die Si02-Teilchen abeschieden werden. Dabei ist es erforderlich, Schichten mit unterschiedlichen optischen Brechungsindizes zu erzeugen. Dieses geschieht durch Dotierung der Si02-Teilchen.In the non-prepublished EP-A-0 134 507, which falls under Article 54 (3) EPC, a method is described which is particularly suitable for the production of so-called preforms for optical fibers made of quartz glass. For this purpose, a silicon dioxide (Si0 2 ) -containing aerosol stream is generated by chemical conversion of gaseous silicon tetrachloride (SiCl 4 ) and water vapor (H 2 0) in a reactor at 500 ° C to 1,000 ° C. In the aerosol stream there is a rod-shaped carrier body on which the Si0 2 particles are deposited. It is necessary to create layers with different optical refractive indices. This is done by doping the Si0 2 particles.

Die Erzeugung der Si02-Teilchen erfolgt in einem Reaktor in einem Temperaturbereich von 500 °C bis 1 000 °C durch eine Hydrolysereaktion gemäß der FormelThe Si0 2 particles are generated in a reactor in a temperature range from 500 ° C. to 1000 ° C. by means of a hydrolysis reaction according to the formula

Figure imgb0001
Figure imgb0001

Eine Dotierung derartig hergestellter Si02-Teilchen ist lediglich möglich mit Dotierstoffen, die bei den erwähnten Reaktionsbedingungen in die Quarzmatrix einbaubar sind. Ein derartiger Dotierstoff ist beispielsweise Germaniumoxid (Ge02), das den Brechungsindex von Si02 erhöht. Diese Dotierung erfolgt mit Hilfe einer Hydrolysereaktion gemäß der Formel

Figure imgb0002
die analog zu Formel (1) abläuft.Doping Si0 2 particles produced in this way is only possible with dopants that can be incorporated into the quartz matrix under the reaction conditions mentioned. Such a dopant is, for example, germanium oxide (Ge0 2 ), which increases the refractive index of Si0 2 . This doping takes place with the aid of a hydrolysis reaction according to the formula
Figure imgb0002
 which proceeds analogously to formula (1).

Für einige optische Brechzahlprofile eines Uchtwellenleiters ist es jedoch erforderlich, den Brechungsindex von SiO2 durch Dotierung zu erniedrigen.For some optical refractive index profiles of an ultraviolet waveguide, however, it is necessary to lower the refractive index of SiO 2 by doping.

Der Erfindung liegt daher die Aufgabe zugrunde, ein gattungsgemäßes Verfahren dahingehend weiterzubilden, daß bei einem SiO2-haltigen Aerosolstrom eine Dotierung der darin enthaltenen Si02-Teilchen möglich wird, die bei Si02 eine Erniedrigung des optischen Brechungsindexes bewirkt.The invention is therefore based on the object of developing a generic method in such a way that, in the case of an SiO 2 -containing aerosol stream, doping of the Si0 2 particles contained therein is possible, which causes a reduction in the optical refractive index in Si0 2 .

Diese Aufgabe wird gelöst durch die im kennzeichnenden Teil des Patentanspruchs 1 angegebenen Merkmale.This object is achieved by the features specified in the characterizing part of patent claim 1.

Ein erster Vorteil der Erfindung besteht darin, daß bei Verwendung von CF2 CI2 das entstehende Fluor in die Si02-Teilchen eingebaut wird. Eine unsicher beherrschbare oberflächliche Adsorption wird vermieden.A first advantage of the invention is that when using CF 2 CI 2, the resulting fluorine is incorporated into the Si0 2 particles. An unsafe controllable surface adsorption is avoided.

Ein zweiter Vorteil besteht darin, daß eine hohe Fluorkonzentration im Siliciumdioxid erreicht wird, so daß eine starke Erniedrigung des optischen Brechungsindexes ermöglicht wird.A second advantage is that a high fluorine concentration is achieved in the silicon dioxide, so that the optical refractive index can be greatly reduced.

Die Erfindung wird im folgenden anhand eines Ausführungsbeispiels näher erläutert.The invention is explained in more detail below using an exemplary embodiment.

In einer Versuchsreihe werden Si02-Teilchen gemäß Formel (1) hergestellt. Diese SiO2-Teilchen besitzen einen Durchmesser von ungefähr 0,3 µm und werden in der Fachliteratur als Glasruß oder mit dem englischen Ausdruck « soot bezeichnet. Dabei werden dem dampfförmigen Siliciumtetrachlorid (SiCl4) verschiedene fluorhaltige Gase und/oder Dämpfe in bestimmten Verhältnissen beigemengt und der entstandene Glasruß (« soot ») auf seinen Fluorgehalt untersucht. Das Ergebnis ist in der folgenden Tabelle dargestellt :

Figure imgb0003
In a series of experiments, Si0 2 particles according to formula (1) are produced. These SiO 2 particles have a diameter of approximately 0.3 μm and are referred to in the specialist literature as glass soot or with the English expression “soot”. Various fluorine-containing gases and / or vapors are added to the vaporous silicon tetrachloride (SiCl 4 ) in certain proportions and the resulting glass soot («soot») is examined for its fluorine content. The result is shown in the following table:
Figure imgb0003

Von den verwendeten Gasen und/oder Dämpfen zeigt lediglich CF2CI2 einen Dotierungseffekt in einer erwünschten Größenordnung. CF4 und SFs ergeben eine vemachlässigbare Fluordotierung, wohl deshalb, weil sich diese Gase bei einer Temperatur von 700 °C noch nicht nennenswert zersetzen. Ein wichtiges Ergebnis ist auch, daß der Fluorgehalt (nach einer Dotierung mit CF2CI2 und nach einem Sintervorgang) zum großen Teil erhalten bleibt. Dies kann als Hinweis aufgefaßt werden, daß tatsächlich ein Einbau des Fluors in die Si02-Partikel erfolgt ist und nicht nur eine oberflächliche Adsorption vorliegt. Mit der angegebenen Fluordotierung im Bereich von 1,0 mol % bis 1,8 mol % ist bei Si02 eine Erniedrigung des optischen Brechungsindexes von 0,35 % bis 0,57 % möglich.Of the gases and / or vapors used, only CF 2 CI 2 shows a doping effect of a desired magnitude. CF 4 and SF s result in negligible fluorine doping, probably because these gases do not decompose appreciably at a temperature of 700 ° C. An important result is that the fluorine content (after doping with CF 2 CI 2 and after a sintering process) is largely preserved. This can be interpreted as an indication that the fluorine has actually been incorporated into the SiO 2 particles and that there is not only superficial adsorption. With the specified fluorine doping in the range of 1.0 mol% to 1.8 mol%, a reduction in the optical refractive index of 0.35% to 0.57% is possible with Si0 2 .

Claims (1)

  1. Method for the production of an aerosol stream, in which an aerosol containing silicon dioxide is produced from a mixture of gas and/or vapour in a reactor by a flame-free chemical reaction of vaporous silicon tetrachloride with water vapour, characterised thereby, that a fluorine-doped silicon dioxide with an optical refractive index, which is reduced by comparison with pure silicon dioxide, is produced by addition of a vaporous halogenated hydrocarbon, which contains fluorine and is substantially represented by the chemical formula CF2Cl2, to the mixture of gas and/or vapour and that the aerosol stream containing silicon dioxide is conducted through a stream of gas and/or vapour substantially free of aerosol.
EP85107856A 1984-09-21 1985-06-25 Method for producing an aerosol stream Expired - Lifetime EP0175068B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85107856T ATE49188T1 (en) 1984-09-21 1985-06-25 PROCESS FOR PRODUCING AN AEROSOL STREAM.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19843434674 DE3434674A1 (en) 1984-09-21 1984-09-21 METHOD FOR PRODUCING A AEROSOL FLOW
DE3434674 1984-09-21

Publications (3)

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EP0175068A2 EP0175068A2 (en) 1986-03-26
EP0175068A3 EP0175068A3 (en) 1987-09-02
EP0175068B1 true EP0175068B1 (en) 1990-01-03

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EP85107856A Expired - Lifetime EP0175068B1 (en) 1984-09-21 1985-06-25 Method for producing an aerosol stream

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US (1) US4610892A (en)
EP (1) EP0175068B1 (en)
JP (1) JPS6177628A (en)
AT (1) ATE49188T1 (en)
CA (1) CA1241877A (en)
DE (2) DE3434674A1 (en)
FI (1) FI79084C (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3118822B2 (en) * 1990-09-07 2000-12-18 住友電気工業株式会社 Method for manufacturing glass articles
DE19725955C1 (en) * 1997-06-19 1999-01-21 Heraeus Quarzglas Quartz glass preform production for optical fibre manufacture
EP1010672A1 (en) 1998-12-17 2000-06-21 PIRELLI CAVI E SISTEMI S.p.A. Method and apparatus for forming an optical fiber preform by combustionless hydrolysis
US6723435B1 (en) * 2001-08-28 2004-04-20 Nanogram Corporation Optical fiber preforms
US20080285927A1 (en) * 2006-04-24 2008-11-20 Sterlite Optical Technologies Ltd. Single Mode Optical Fiber Having Reduced Macrobending and Attenuation Loss and Method for Manufacturing the Same

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4083708A (en) * 1976-09-15 1978-04-11 Exxon Research & Engineering Co. Forming a glass on a substrate
CA1080562A (en) * 1977-02-10 1980-07-01 Frederick D. King Method of and apparatus for manufacturing an optical fibre with plasma activated deposition in a tube
JPS5927728B2 (en) * 1977-08-11 1984-07-07 日本電信電話株式会社 Manufacturing method of sooty glass rod
US4233045A (en) * 1978-11-27 1980-11-11 Corning Glass Works Apparatus and method for making optical filament preform
US4378987A (en) * 1981-10-15 1983-04-05 Corning Glass Works Low temperature method for making optical fibers
DE3203349A1 (en) * 1981-11-28 1983-06-09 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt METHOD AND DEVICE FOR PRODUCING AN OPTICAL GLASS FIBER WITH A LOW OH ION CONTENT
DE3206177A1 (en) * 1982-02-20 1983-08-25 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Process for the production of a preform from which optical fibres can be drawn
US4440558A (en) * 1982-06-14 1984-04-03 International Telephone And Telegraph Corporation Fabrication of optical preforms by axial chemical vapor deposition
DE3304721A1 (en) * 1983-02-11 1984-08-16 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt METHOD FOR PRODUCING A PREFORM FOR LIGHTWAVE GUIDES
DE3326043A1 (en) * 1983-07-20 1985-02-07 Licentia Gmbh METHOD FOR PRODUCING A AEROSOL FLOW AND THE USE THEREOF
WO1985002837A1 (en) * 1983-12-22 1985-07-04 American Telephone & Telegraph Company Fabrication of high-silica glass article

Also Published As

Publication number Publication date
DE3575123D1 (en) 1990-02-08
JPS6177628A (en) 1986-04-21
ATE49188T1 (en) 1990-01-15
FI79084C (en) 1989-11-10
CA1241877A (en) 1988-09-13
FI853619L (en) 1986-03-22
EP0175068A2 (en) 1986-03-26
FI79084B (en) 1989-07-31
US4610892A (en) 1986-09-09
FI853619A0 (en) 1985-09-20
EP0175068A3 (en) 1987-09-02
DE3434674A1 (en) 1986-04-03

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